Packaging of an integrated circuit die is receiving an increasing amount of attention from the manufacturers of electronic components. Packaging designers face more serious challenges as the circuit density of a given size integrated circuit die increases. The circuit density of a particular die typically plays a major role in the number of input/output signals associated with operation of the die. An increase in the input/output count affects a number of factors which must be considered by packaging designers.
Firstly, a high input/output count requires a correspondingly high interconnection density, both with respect to electrical couplings within the package and with respect to electrical couplings from the package to outside circuitry. A dense interconnection scheme is susceptible to electrical shorts.
A second factor follows from the first. An integrated circuit die having a dense interconnection scheme is typically associated with a relatively low manufacturing yield. Thus, a packaging design which facilitates testing at the die level is desirable.
A third factor involves heat dissipation. A dense integrated circuit die often requires a larger package so that the package is able to dissipate more heat than packages used for less dense integrated circuit dies. An ever present goal in the electronic industry is one of miniaturization. Consequently, packaging designers attempt to provide packages which require a minimal amount of real estate on a printed circuit board.
Yet another important factor is cost. While packaging significantly affects the cost of a packaged integrated circuit die, packaging should not dominate the overall cost.
The most common packages are dual-in-line packages (DIP), leadless chip carriers, leaded chip carriers, and pin-grids. Interconnection schemes to the contact pads of the die may be by wire bonding miniature wires to the pads or by flip-chip solder bonding to solder bumps formed at the pads. In either case, the interconnection scheme is difficult to connect to a testing device prior to completion of the packaging. The package itself is typically a ceramic or plastic material Devices of this type are described in U.S. Pat. Nos. 4,423,468 to Gatto et al., 4,493,145 to Honda, 4,697,204 to Mita et al. and 4,682,207 to Akasaki et al.
Another interconnection technique is referred to as tape automated bonding and is described in U.S. Pat. No. 4,899,207 to Hallowell et al. This technique utilizes a plurality of conductive fingers having inner leads arranged in a pattern corresponding to the input/output pads of a particular integrated circuit die. The inner leads are bonded to the input/output pads, while radially outward outer leads are bonded to a printed circuit board or the like. One benefit of tape automated bonding is that the integrated circuit die may be easily tested prior to attachment of the outer leads to the printed circuit board.
It is an object of the present invention to provide an interconnection and packaging approach for integrated circuit dies which facilitates testing at the die level and which promotes miniaturization and high yield. It is a further object to provide such an approach which is cost efficient.